Originally Posted by Greg58
Now that I got to my computer let me explain, in nascar engines the bore has gone up over the years and the stroke shortened. This has proven to increase the low end torque greatly. A 350 ci chevy small block has a bore of 4 inches, the current nationwide 358ci toyota engine has a bore of 4.470 inches. nationwide engines have about 200 less hp than sprint cup engines which specs. are hard to find.
That's very odd, then. When Dodge first got back into NASCAR racing Petty Enterprizes had to get rid of over 200 engines that were overbored to NASCAR specs. The reason is Large bore, short stroke motors can be spun faster than a square bore/stroke set-up. I have a Pontiac 151 Iron Duke motor. In reality it's a Jeep version but no real difference except a stiffened block and their own head. It has a 4.00 inch bore with a 3 inch stroke. This is the same dimentions as the 60's Z28 motor that were famous for 8500 RPM blasts down a quarter mile. The Iron Duke won't spin like that due to sucky intake ports but they easily spin to 7000 RPM until they run out of air.
I think what it is is Toyota has a bore spacing of 4.470 and not a bore of 4.470 or you would hear screaming from the other 3 manufacturers.